An attempt is made to present a simplified theoretical formulation of the Fowler-Nordheim field emission (FNFE) in quantum wires (Qws) of non-linear optical materials on the basis of a newly formulated electron dispersion law by considering various types of anisotropies of the energy band constants within the framework of k.p formalism. We also study FNFE from Qws of III-V, II-VI and Bismuth by using the appropriate band models. Taking Qws of CdGeAs 2, InAs, InSb, GaAs, Hg 1-xCd xTe and In 1-xGa xAsP 1-y lattice matched to InP, CdS and Bi as examples, we observe that, the FNFE increases with increasing film thickness due to the existence van- Hove singularity and the magnitude of the quantum jumps are not of same height indicating the signature of the band structure of the material concerned. The appearance of the humps of the respective curves is due to the redistribution of the electrons among the quantized energy levels when the quantum numbers corresponding to the highest occupied level changes from one fixed value to the others. Although the field current varies in various manners with all the variables in all the cases as evident from all the curves, the rates of variations are totally band-structure dependent. All the results as derived in this paper get transformed in to the well known Fowler-Nordheim formula under certain limiting conditions, and thus confirming the compatibility test. © 2012 American Scientific Publishers. All rights reserved.